Generally, when a portion inside a body requires treatment or when biological tissue inside a body is to be examined by means of operations performed outside the body using an endoscope, there are cases when a plurality of treatment tools such as, for example, needle scalpels and gripping forceps are used consecutively. In such cases, conventionally, operations are performed such as inserting a selected treatment tool into the body through a channel that is provided inside an insertion portion of the endoscope, and then extracting the treatment tool to the outside of the body after predetermined treatment has been performed, and then once more inserting another treatment tool into the channel.
When inserting a treatment tool into the channel, it is currently necessary to insert the elongated treatment tool extremely carefully into the narrow channel through a forceps channel provided in the endoscope, so that not only is the task laborious, but it also requires a high level of concentration. Moreover, in recent years, treatment tool insertion portions having various outer diameters, and treatment tools in which the treatment tool distal end portions and the treatment tool insertion portions have different outer diameters have been proposed to suit the type of operation or to match the outer diameter of the channel of an endoscope.
Because of this, in order to provide insertion/extraction devices that perform these operations to insert or extract a treatment tool into a channel automatically, and that are able to handle treatment tools having different diameters, devices have been proposed in which there is provided separately from the insertion/extraction roller a rotary solenoid that switches between a state in which the roller and the treatment tools having different diameters are in contact and a state in which they are mutually isolated (see, for example, Patent document 1), and also devices have been proposed in which rollers having different diameters can be replaceably mounted in accordance with the outer diameter of the treatment tool insertion portion which is being used (see, for example, Patent document 2).    [Patent document 1] Japanese Patent Application, First Publication No. Sho57-190541    [Patent document 2] Japanese Patent Application, First Publication No. Hei9-492